Sea Tel 9797A-27, Installation And Operation Manual

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Basic System Information 9797A-27 C-Band TXRX
3-6
3.3.1. Antenna ADE Assembly
The Above Decks Equipment consists of an Antenna
Pedestal inside a Radome assembly. The pedestal
consists of a satellite antenna dish & feed with a linear,
or a circular Low Noise Block converter (LNB) with
polarization motor mounted on a stabilized antenna
pedestal. The radome provides an environmental
enclosure for the antenna pedestal assembly inside it.
This keeps wind, water condensation and salt-water
spray off the antenna pedestal assembly. This prevents
damage and corrosion that would shorten the expected
life span of the equipment.
Two coaxial cables are connected from the antenna
radome assembly to the below decks equipment. One
of these cables includes the Antenna Control signaling
and IF, the other cable carries the other IF signal.
These cables ultimately provide the input/output signals
into/out of the satellite modem.
3.3.2. Antenna Control Unit
The Antenna Control Unit allows the operator to control and monitor the antenna pedestal with dedicated
function buttons, LED’s and a 2 line display. The ACU and its Terminal Mounting Strip are normally
mounted in a standard 19” equipment rack. The ACU should be mounted in the front of the equipment
rack where it is easily accessible. The Terminal Mounting Strip is normally mounted on the rear of the
equipment rack. It is recommended that the antenna control panel be mounted near one of the Satellite
Receiver locations where you can see the television screen while you are controlling the antenna.
The Antenna Control Unit is connected to the antenna, ships Gyro Compass and to the GPS Engine
(when included).
Figure 3-4 DAC Antenna Control Unit
The Antenna Control Unit (ACU) communicates via an RS-422 serial data link with the Pedestal Control
Unit (PCU) located on the antenna. This control signal is sent up the Antenna Control cable along with the
DC voltage for the antenna power. The Pedestal Control Unit stabilizes the antenna against the ship's roll,
pitch, and turning motions. The ACU is the operator interface to the PCU and provides the user with a
choice of positioning commands to point the antenna, search commands to find the satellite signal and
tracking functions to maintain optimum pointing.
Figure 3-3 Series 97 TXRX Above Decks Equipment